Sunday, February 20, 2011

Chemistry Form 5: Chapter 1 - Catalyst Affects the Rate of Reaction

Catalyst is a chemical substance that change the rate of chemical reaction.

Characteristics of catalyst:
  • Catalyst remains chemically unchanged during reaction. Its chemical composition still the same before and after reaction.
  • Catalyst only change the rate of reaction.
  • Catalyst does not change the quantity of the product formed.
  • Catalyst is specific in its action.
  • Only a small amount of catalyst is needed to achieve a big increase in rate of reaction.
 How catalyst increase the rate of reaction:
  • When a positive catalyst is used in a chemical reaction, it enables the reaction to occur through an alternative path which requires lower activation energy.
  • As a result, more colliding particles are able to overcome the lower activation energy.
  • This causes the frequency of effective collision to increase.
  • Hence, the rate of reaction increases.
Decomposition of hydrogen peroxide by catalyst of manganese (IV) oxide

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